World Leaders in Ultra-Pure Heating
Revision 10
www.heateflex.com
01/17/13
405 E. Santa Clara St.
Arcadia, CA 91006-7218
Tel: (626) 599-8566 Fax: (626) 599-9567
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4.2 Shellside (Steam) Safety Mechanisms
The unit operates normally on 120°C steam, which is supplied by the customer‟s in-house
steam supply and should have provision to limit its pressure to a range of 12 to 15 psig. The
setting for the steam pressure relief valve on the unit is set at 15 psig.
The steam supply to the unit can be manually or automatically shut down by means of a
pneumatic ball valve mounted at the inlet to the exchanger shell. The Auto-Shutdown System
is automatically activated by any of the several alarm conditions: Process Over Temperature,
Low Process Pressure, Shellside Over Temperature, D.I. Pressure Relief Venting, Steam
Pressure Relief Venting, Hot Valve Over Temperature, and Low Flow Rate. In addition, when
the Auto-Isolation is set to “Bypass” mode (when no flow is present), manual initiation on the
System Status screen of the main or remote panels, or loss of power at the main unit the Auto-
Shutdown System will also be initiated.
When an Auto-Shutdown occurs, the pneumatic ball valve will close, audio alarms on both the
main and remote panels will be energized, and the appropriate alarm screen will appear to
identify the cause of the shutdown. An external input is also provided so the Auto-Shutdown
System can be activated from a remote location by the user or interfaced to another piece of
equipment.
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4.2.1 Shellside (Steam) Over-Pressure
A pressure relief valve that is factory set at 15 psig provides over-pressure protection. If for
any reason the pressure in the vessel exceeds this value, the valve will open to vent off the
excess pressure, and then the system will need to be reset. This pressure and temperature
combination is well below the working pressure / temperature range for the unit‟s PFA tubing
and vessel but the basic design of the equipment dictates that the shellside pressure be lower
than the process pressure at all times, therefore the 15 psig maximum to prevent backflow to
the process fluid should a leak occur.
